1. Field of the Invention
The invention relates to a method of structuring multicrystalline silicon surfaces.
2. Background Art
Due to the different crystal orientations of multicrystalline silicon surfaces, a wet chemical surface structuring thereof using alkaline substances is impossible. The wet chemical surface texturing of multicrystalline silicon is therefore generally performed using an acidic texturing solution. The acidic texturing solution usually requires an addition of hydrofluoric acid although hydrofluoric acid on its own does not have a texturing effect on silicon surfaces. Texturing of multicrystalline silicon surfaces can thus only be performed by means of acid mixtures. Compared to pure acids, an environmentally friendly disposal of such mixtures is very complicated and expensive. Furthermore, the use of hydrofluoric acid requires extensive safety precautions because of its high toxicity, which leads to even higher costs. Finally, the use of the above-mentioned acid mixtures produces highly toxic gases. The temperature of the acid mixtures usually needs to be reduced to between 8° C. and 10° C., which results in additional energy costs. Another drawback of the use of acid mixtures is their low process stability. The concentration ratio needs to be strictly adhered to in order to guarantee a constant structuring quality but as the acid mixture ratio continuously changes in the texturing process, the bath composition needs to be monitored and adapted continuously.